Role of basal cells in nasal polyp epithelium in the pathophysiology of eosinophilic chronic rhinosinusitis (eCRS)

BACKGROUND

Basal cell hyperplasia is commonly observed in nasal polyp epithelium of eosinophilic chronic rhinosinusitis (eCRS). We examined the function and mechanisms of basal cell hyperplasia in the pathophysiology of eCRS.

METHODS

We found that normal human bronchial epithelial (NHBE) cells obtained basal cell characteristics when cultured with PneumaCult™-Ex Plus Medium. Most of the cells passaged three times expressed basal cell surface markers CD49f and CD271 by flow cytometry, and basal cell nuclear marker p63 by immunohistochemical staining. We named these NHBE cells with basal cell characteristics cultured Basal-like cells (cBC), and NHBE cells cultured with BEGM™ cultured Epithelial cells (cEC). The characteristics of cBC and cEC were examined and compared by RNA sequencing, RT-PCR, ELISA, and cell proliferation studies.

RESULTS

RNA sequencing revealed that cBC showed higher gene expression of thymic stromal lymphopoietin (TSLP), IL-8, TLR3, and TLR4, and lower expression of PAR-2 compared with cEC. The mRNA expression of TSLP, IL-8, TLR3, and TLR4 was significantly increased in cBC, and that of PAR-2 was significantly increased in cEC by RT-PCR. Poly(I:C)-induced TSLP production and LPS-induced IL-8 production were significantly increased in cBC. IL-4 and IL-13 stimulated the proliferation of cBC. Finally, the frequency of p63-positive basal cells was increased in nasal polyp epithelium of eCRS, and Ki67-positive proliferating cells were increased in p63-positive basal cells.

CONCLUSIONS

Type 2 cytokines IL-4 and IL-13 induce basal cell hyperplasia, and basal cells exacerbate type 2 inflammation by producing TSLP in nasal polyp of eCRS.

SARS-CoV-2 induces inflammation and intracranial infection through the olfactory epithelium-olfactory bulb pathway in non-human primates

We examined the histopathological changes in the olfactory mucosa of cynomolgus and rhesus macaque models of SARS-CoV-2 infection. SARS-CoV-2 infection induced severe inflammatory changes in the olfactory mucosa. A major histocompatibility complex (MHC) class II molecule, HLA-DR was expressed in macrophage and supporting cells, and melanocytes were increased in olfactory mucosa. Supporting cells and olfactory neurons were infected, and SARS-CoV-2 N protein was detected in the axons of olfactory neurons and in olfactory bulbs. Viral RNA was detected in olfactory bulbs and brain tissues. The olfactory epithelium-olfactory bulb pathway may be important as a route for intracranial infection by SARS-CoV-2.

Increase in the prevalence of follicular regulatory T cells correlates with clinical efficacy of sublingual immunotherapy with house dust mites

BACKGROUND

Allergic rhinitis (AR) impairs quality of life and affects nearly 40% of the Japanese population. Sublingual immunotherapy (SLIT) is the disease-modifying treatment for AR, but requires the selection of a biomarker associate with clinical efficacy in patients with AR who are treated with SLIT. The present study sought to examine objective biomarkers used for assessing the clinical efficacy of SLIT.

METHODS

The authors examined the effects of 1 year of SLIT treatment with house dust mites (HDMs) using peripheral blood mononuclear cells (PBMCs) and serum from patients with AR. The prevalences of follicular regulatory T (Tfr), type 2 follicular helper T (Tfh2), type 2 helper T (Th2), conventional regulatory T (Treg), and type 1 regulatory T (Tr1) cells were examined by flow cytometry. Serum concentrations of HDM-specific IgA, IgE, and IgG4 antibodies, and HDM-induced production of interleukin (IL) 5 and IL-10 from cultured PBMCs were evaluated by enzyme-linked immunosorbent assay.

RESULTS

Following 1 year of SLIT, the prevalences of Tfr, conventional Treg, and Tr1 cells were significantly increased, whereas that of Th2 cells and Tfh2 cells were significantly decreased; the serum concentration of HDM-specific IgG4 was significantly increased; and HDM-induced production of IL-5 from PBMCs was significantly decreased, while that of IL-10 was significantly increased. The increase in the prevalence of Tfr cells after SLIT correlated positively with the improvement of clinical symptom scores.

CONCLUSION

An increase in Tfr cells may play an important role in SLIT, and may be a useful indicator for the clinical efficacy of SLIT.

Therapeutic Potential of Valproic Acid for Postviral Olfactory Dysfunction: A Single-Arm Pilot Study

OBJECTIVES

Although some patients with postviral olfactory dysfunction (PVOD) recover spontaneously, many others are left with the degree of smell loss and there are no established drugs for the treatment of patients with PVOD. Valproic acid (VPA) has been widely used for the treatment of epilepsy. Its potential neuroregenerative effects have been shown via animal studies. This is the first study to treat PVOD patients with VPA. This open-label, single-arm, phase II study was conducted to investigate the effects of VPA in patients with PVOD.

METHODS

The patients received oral tablets of VPA 200 mg twice a day for 24 weeks. In total, 11 patients with PVOD were recruited. Oder scores of recognition and detection threshold (measured with a T&T olfactometer), and visual analog scale were examined during the treatment.

RESULTS

All odor scores significantly improved over time. Although the mean duration of olfactory dysfunction in this study was 11.5 months, both odor recognition threshold and odor detection threshold scores significantly improved 4 weeks after treatment initiation compared to the pre-treatment threshold scores. The olfactory recovery rates in patients treated with VPA were clearly better than those we previously reported in PVOD patients who received Toki-shakuyaku-san, the traditional treatment in Japan. The olfactory recovery rates of patients with PVOD at 12 weeks and 24 weeks of VPA treatment were both 77.8%, and the olfactory cure rates at 12 weeks and 24 weeks of VPA treatment were 33.3% and 44.4%, respectively. No serious adverse events were observed.

CONCLUSIONS

VPA seems to be a safe treatment option in patients with PVOD. The effects of VPA treatment for PVOD patients should be studied with a controlled study design in the future.

A Histochemical Analysis of Neurofibrillary Tangles in Olfactory Epithelium, a Study Based on an Autopsy Case of Juvenile Alzheimer’s Disease

The pathological changes of Alzheimer’s disease (AD) begin 10–20 years before clinical onset, and it is therefore desirable to identify effective methods for early diagnosis. The nasal mucosa is a target tissue for measuring AD-related biomarkers because the olfactory nerve is the only cranial nerve that is exposed to the external environment. We describe an autopsy case of rapidly advanced juvenile AD (JAD), focusing on the olfactory system. The formation of senile plaques, neurofibrillary tangles (NFTs), and neuropil threads was examined in the temporal cortex, hippocampus, olfactory bulb, and olfactory and respiratory epithelia in the bilateral olfactory clefts. Neurodegenerative changes in the olfactory and respiratory epithelia and the pathological deposition of amyloid β42 (Aβ42) and phosphorylated tau were also examined. As a result, senile plaques, NFTs, and neuropil threads were found in the temporal cortex, hippocampus, and olfactory bulb. NFTs were also found in the olfactory epithelium. Degenerated olfactory cells and their axons stained positive for phosphorylated tau. Supporting cells in the degenerated olfactory epithelium stained positive for Aβ42. In conclusion, pathological biomarkers of AD were expressed in the degenerated olfactory epithelium of this JAD patient. This observation suggests that nasal samples may be useful for the diagnosis of AD.

Nasal polyp fibroblasts (NPFs)-derived exosomes are important for the release of vascular endothelial growth factor from cocultured eosinophils and NPFs

OBJECTIVE

Significant eosinophil infiltration and tissue remodeling are common characteristics of conditions associated with chronic airway inflammation, such as chronic rhinosinusitis with nasal polyp and bronchial asthma. This study was designed to elucidate the role of eosinophil-fibroblast interactions in tissue remodeling during chronic airway inflammation.

METHODS

Peripheral blood eosinophils or EoL-1 eosinophilic leukemia cells were cocultured with nasal polyp fibroblasts (NPFs). Coculture-induced release of exosomes, major components of extracellular vesicles (EVs), and a profibrotic cytokine, vascular endothelial growth factor (VEGF), were evaluated by enzyme-linked immunosorbent assay.

RESULTS

Eosinophil-NPF interactions stimulated the release of exosomes and VEGF into culture supernatants. Coculture-induced release of exosomes was stimulated earlier than VEGF release, at 3 h of incubation. The average size of the EVs released by NPFs was 133 ± 3.6 nm. NPF-derived EVs (exosome concentration: 25 pg/mL) significantly stimulated VEGF release from EoL-1 cells. Pretreatment of NPFs with exosome inhibitor, GW4869 or DMA attenuated the release of exosomes and VEGF from cocultured EoL-1 cells and NPFs.

CONCLUSION

The results of this study indicate that eosinophil-fibroblast interactions are important in the pathophysiology of tissue remodeling in eosinophil-predominant airway inflammation and that NPF-derived exosomes play a crucial role in the release of VEGF.

Anti-inflammatory roles of interleukin-35 in the pathogenesis of Japanese cedar pollinosis

Background

Interleukin (IL)-35 has been recently identified as an anti-inflammatory cytokine in allergic inflammation. However, its biological role in the pathogenesis of allergic rhinitis has not been fully elucidated.

Objective

The purpose of this study was to investigate the anti-inflammatory activity of IL-35 in the pathogenesis of allergic rhinitis in patients with Japanese cedar pollinosis (JCP).

Methods

Peripheral blood mononuclear cells were collected from healthy controls and JCP patients during the off-season for pollen. Peripheral blood mononuclear cells were incubated with Cry j 1, a major allergen of Japanese cedar pollen and production of IL-5, IL-13, and IL-35 were measured by enzyme-linked immunosorbent assay. Th2 (CD4⁺ST2⁺) cells and group 2 innate lymphoid cells were isolated from peripheral blood mononuclear cells of JCP patients, and the inhibitory effects of IL-35 on cell differentiation, proliferation and mRNA expression of IL-5, IL-13, and GATA3 were examined. B cells were also isolated and the effects of IL-35 on total IgE production were examined.

Results

Cry j 1-induced production of IL-5 and IL-13 was significantly increased in peripheral blood mononuclear cells from JCP patients, whereas Cry j 1-induced IL-35 production was significantly decreased compared with healthy controls. IL-35 significantly inhibited Th2 cell differentiation, group 2 innate lymphoid cell proliferation, and mRNA expression of IL-5, IL-13, and GATA3 in Th2 cells and group 2 innate lymphoid cells. IL-35 also inhibited IgE production from B cells.

Conclusion

IL-35 is an important anti-inflammatory cytokine in JCP, and its biological roles include the downregulation of Th2 cells and group 2 innate lymphoid cells, and the inhibition of IgE production from B cells. These findings demonstrate that IL-35 may have the potential to exert anti-allergic effects for the treatment of allergic rhinitis.

17,18-Epoxyeicosatetraenoic Acid Inhibits TNF-α-Induced Inflammation in Cultured Human Airway Epithelium and LPS-Induced Murine Airway Inflammation

BACKGROUND

17,18-Epoxyeicosatetraenoic acid (17,18-EpETE), an eicosapentaenoic acid metabolite, is generated from dietary oil in the gut, and antiinflammatory activity of 17,18-EpETE was recently reported.

OBJECTIVE

To evaluate the inhibitory effects of 17,18-EpETE in airway inflammation, we examined in vitro and in vivo effects on mucus production, neutrophil infiltration, and cytokine/chemokine production in airway epithelium.

METHODS

Nasal tissue localization of G protein-coupled receptor 40 (GPR40), a receptor of 17,18-EpETE, was determined by immunohistochemical staining. Expression of GPR40 mRNA in nasal mucosa of chronic rhinosinusitis (CRS) patients and control subjects was determined by reverse transcription-polymerase chain reaction (RT-PCR). The in vitro effects on airway epithelial cells were examined using normal human bronchial epithelial cells and NCI-H292 cells. To examine the in vivo effects of 17,18-EpETE on airway inflammation, we induced goblet cell metaplasia, mucus production, and neutrophil infiltration in mouse nasal epithelium by intranasal lipopolysaccharide (LPS) instillation.

RESULTS

GPR40 is mainly expressed in human nasal epithelial cells and submucosal gland cells. RT-PCR analysis revealed that the expression of GPR40 mRNA was increased in nasal tissues from CRS patients compared with those from control subjects. 17,18-EpETE significantly inhibited tumor necrosis factor (TNF)-α-induced production of interleukin (IL)-6 , IL-8, and mucin from cultured human airway epithelial cells dose dependently, and these antiinflammatory effects on cytokine production were abolished by GW1100, a selective GPR40 antagonist. Intraperitoneal injection or intranasal instillation of 17,18-EpETE significantly attenuated LPS-induced mucus production and neutrophil infiltration in mouse nasal epithelium. Inflammatory cytokine/chemokine production in lung tissues and bronchoalveolar lavage fluids was also inhibited.

CONCLUSION

These results indicate that 17,18-EpETE plays a regulatory role in mucus hypersecretion and neutrophil infiltration in nasal inflammation. Local or systemic administration may provide a new therapeutic approach for the treatment of intractable airway disease such as CRS.

Recovery Over Time and Prognostic Factors in Treated Patients with Post-Infectious Olfactory Dysfunction: A Retrospective Study

Objectives:

The aims of the present study were to clarify the time-course of olfactory recovery and the prognostic factors in PIOD patients treated with Toki-shakuyaku-san (TSS).

Methods:

A retrospective cohort study of patients with PIOD was conducted by reviewing patients’ medical records. This study included patients who received TSS or a combination of TSS and zinc sulfate. Olfactory function was examined by T&T olfactometer at each 3-monthly follow-up visit. Patients with normal and mild olfactory dysfunction were excluded. Gender, age, treatment, duration of disease until the first visit and olfactory function scores of the T&T olfactometer at the first visit were analyzed as candidate clinical predictors of recovery.

Results:

A total of 82 PIOD patients with ages ranging from 16 to 79 years were included. The mean duration of follow-up was 14.5 months (range 3-45 months). The number of patients with olfactory recovery increased for 24 months and the cumulative recovery rate was 77.3%. In about 60% of patients, olfactory recovery occurred within 6 months. Multivariate analysis showed that younger age (<65 years) and residual olfactory function were significantly associated with good olfactory recovery.

Conclusions:

We revealed recovery rates over time in patients with PIOD. The recovery of olfactory function often occurred during the early period (≤6 months). However, the number of patients with olfactory recovery increased for a long-term of 24 months after the first visit. Residual olfactory function and younger age were prognostic factors exactly. TSS may be a useful therapeutic agent for patients with PIOD. We believe that these results provide important information that is useful for counseling patients with PIOD.

Evidence for the induction of Th2 inflammation by group 2 innate lymphoid cells in response to prostaglandin D2 and cysteinyl leukotrienes in allergic rhinitis

BACKGROUND

Group 2 innate lymphoid cells (ILC2s) play important roles in allergic inflammation. However, their roles in the pathophysiology of allergic rhinitis (AR) are poorly understood.

OBJECTIVE

Prevalence of ILC2s in the inferior nasal turbinate (INT) tissues and the activating mechanisms of ILC2s were examined in patients with house dust mite (HDM)-induced AR.

METHODS

Eighteen patients with HDM-induced AR and 13 control subjects were recruited. Fresh INT tissues and peripheral blood mononuclear cells (PBMCs) were analysed using flow cytometry. Nasal lavage fluids (NLF) were collected at 10 minutes after the nasal provocation test (NPT) with HDM disc, and released mediators were measured by ELISA. Sorted ILC2s were cultured and stimulated with mediators associated with AR.

RESULTS

The prevalence of ILC2s was significantly increased in nasal mucosa of patients with HDM-induced AR, and it was positively correlated with the number of infiltrating eosinophils. ILC2s in the INT tissues expressed a prostaglandin D₂ (PGD₂ ) receptor, chemoattractant receptor-homologous molecule-expressed TH2 cells (CRTH2) and a cysteinyl leukotriene (cysLTs) receptor, CysLT1. After NPT, the number of eosinophils and concentrations of PGD₂ and cysLTs were significantly increased in the NLF from AR patients. PGD₂ and cysLTs significantly induced IL-5 production from cultured PBMC-derived ILC2s dose-dependently. PGD₂ -induced and cysLTs-induced productions of IL-5 and IL-13 from ILC2s were completely inhibited by ramatroban, a dual CRTH2 and thromboxane receptor antagonist, and montelukast, a CysLT1 antagonist, respectively.

CONCLUSIONS

PGD₂ -CRTH2 and cysLTs-CysLT1 axes may activate tissue-resident ILC2s to produce Th2 cytokines, IL-5 and IL-13, leading to the development of allergic inflammation in AR.

Immunological effects of sublingual immunotherapy with Japanese cedar pollen extract in patients with combined Japanese cedar and Japanese cypress pollinosis

Sublingual immunotherapy (SLIT) with Japanese cedar (JCe) pollinosis was expected to be effective for Japanese cypress (JCy) pollinosis. However, only a half of JCy pollinosis patients clinically improved. Therefore, we examined the immunological effect of SLIT for JCy pollinosis. Peripheral blood mononuclear cells (PBMCs) from patients with JCe and JCy pollinosis who did and did not receive SLIT were incubated with Cry j 1, Cha o 1 and Cha o 3 antigens. Basophil activation test (BAT) were performed. Production of IL-5 and IL-17 induced by antigens was inhibited in the SLIT group. Cry j 1-specific production of IL-10 was increased, and serum Cry j 1-specific IgE and -IgG4 were elevated. However, Cha o 1- or Cha o 3-specific production of IL-10 and specific IgG4 was not increased. Antigens-specific BAT did not decrease after SLIT. New SLIT with JCe and JCy is needed for patients with combined JCe and JCy pollinosis.

Soluble ST2 suppresses IL-5 production by human basophilic KU812 cells, induced by epithelial cell-derived IL-33

BACKGROUND

Epithelial cell-derived IL-33 has an important role in the initiation and activation of innate allergic inflammation. IL-33 acts as a cytokine through the ST2 receptor (ST2L) and it stimulates the production of Th2 cytokines. Soluble ST2 (sST2) may regulate Th2 responses by neutralizing the activity of IL-33. Basophils express ST2L and produce IL-5 in response to IL-33. However, the role of the epithelial cell-basophil interaction and sST2 in IL-5 production remains unclear.

METHODS

Cultured human bronchial epithelial (hBE33) cells, that contained the human IL-33 gene (i.e., hBE33 cells) and a human basophilic cell line, KU812 cells, were used to study the epithelial cell-basophil interaction in the production of IL-5 induced by HDM.

RESULTS

At 15 min after incubation, HDM stimulated the rapid release of IL-33 from cultured hBE33 cells. IL-33 and the supernatant of HDM-treated hBE33 cells stimulated IL-5 production from KU812 cells. Anti-IL-33 antibody and anti-ST2 antibody treatment of KU812 cells suppressed IL-5 production, which had been induced by the supernatant of HDM-treated hBE33 cells. The hBE33 cells secreted sST2 in a time-dependent manner. The production of sST2 by KU812 cells co-cultured with hBE33 cells was significantly increased, compared with KU812 cells cultured with the supernatant of hBE33 cells. Soluble ST2 suppressed IL-5 production by KU812 cells, which was induced by the supernatant of HDM-treated hBE33 cells.

CONCLUSIONS

Epithelial cell-derived IL-33 promoted IL-5 production by KU812 cells. The subsequently produced sST2 has important roles in regulating Th2 responses.

A mechanism of interleukin-25 production from airway epithelial cells induced by Japanese cedar pollen

IL-25 likely has vital roles in initiating and activating type-2 immune responses in AR. We hypothesized that the molecules produced IL-25 by allergen-producing organisms such as JC is involved in the pathogenesis of AR. Participants included 13 patients with Japanese cedar pollinosis and 10 HCs. We measured the IL-25 protein concentration in nasal secretions and in culture supernatants of PNECs. NHBE cells were stimulated with pharmacological and immunological agents and JC. The IL-25 concentration in nasal secretions was significantly higher in patients with Japanese cedar pollinosis than in HCs. JC stimulated IL-25 production from PNECs. TNF-α, IL-4, and IL-13 significantly enhanced JC-induced IL-25 production; their activation by serine proteases was sufficient to enhance IL-25 production. Furthermore, the NADPH oxidase activity, including JC enhanced IL-25 production. A better understanding of JC-induced IL-25 production by epithelial cells may allow the development of novel therapeutic and preventive strategies for Japanese cedar pollinosis.

Endogenous Protease Inhibitors in Airway Epithelial Cells Contribute to Eosinophilic Chronic Rhinosinusitis

RATIONALE

Cystatin A and SPINK5 are endogenous protease inhibitors (EPIs) that may play key roles in epithelial barrier function.

OBJECTIVES

To investigate the roles of EPIs in the pathogenesis of chronic rhinosinusitis (CRS).

METHODS

We examined the expression of cystatin A and SPINK5 in the nasal epithelial cells of patients with CRS. Additionally, the in vitro effects of recombinant EPIs on the secretion of the epithelial-derived cytokines IL-25, IL-33, and thymic stromal lymphopoietin in airway epithelial cells, and the in vivo effects of recombinant EPIs in the nasal epithelium of mice exposed to multiple airborne allergens (MAA) were examined.

MEASUREMENTS AND MAIN RESULTS

Compared with control subjects and patients with noneosinophilic CRS, patients with eosinophilic CRS showed significantly lower protein and mRNA expression of cystatin A and SPINK5 in the nasal epithelium. Allergen-induced production of IL-25, IL-33, and thymic stromal lymphopoietin in normal human bronchial epithelial cells was inhibited by treatment with recombinant cystatin A or SPINK5. Conversely, the production of these cytokines was increased when cystatin A or SPINK5 were knocked down with small interfering RNA. Chronic MAA exposure induced goblet cell metaplasia and epithelial disruption in mouse nasal epithelium and decreased the tissue expression and nasal lavage levels of cystatin A and SPINK5. Intranasal instillations of recombinant EPIs attenuated this MAA-induced pathology.

CONCLUSIONS

Cystatin A and SPINK5 play an important role in protecting the airway epithelium from exogenous proteases. The preservation of EPIs may have a therapeutic benefit in intractable airway inflammation, such as eosinophilic CRS.

Severely infected pneumoceles of the frontal sinus in patients with mental retardation and brain atrophy treated by endoscopic sinus surgery

We herein present three cases of abnormally expanded frontal sinuses (pneumoceles) with severe infection in patients with mental retardation and brain atrophy. Two patients previously underwent laryngotracheal separation surgery, and bacteriological examinations of purulent nasal discharge revealed infections caused by drug-resistant bacteria such as Pseudomonas aeruginosa and Acinetobacter baumannii. As conservative medical treatments were ineffective, all three patients were treated by computed tomography-guided endoscopic sinus surgery. This navigation system is useful for safer surgery in the area of anatomic deformity. The clinical findings, possible etiologies and surgical treatment of these cases are discussed.

Thrombin and activated coagulation factor X stimulate the release of cytokines and fibronectin from nasal polyp fibroblasts via protease-activated receptors

BACKGROUND

Nasal epithelial cells and infiltrating eosinophils express tissue factor, and high thrombin activity and excess fibrin deposition are found in nasal secretion and in nasal polyp from patients with chronic rhinosinusitis with nasal polyp (CRSwNP). Activated coagulation factors play important roles not only in thrombosis but also in inflammation through interaction with protease-activated receptors (PAR). However, little is known about the effects of activated coagulation factors on the release of cytokines and extracellular matrix from nasal polyp fibroblasts (NPF).

PURPOSE

The purpose of this study was to analyze the expression of PARs, which are receptors for activated coagulation factors, on NPFs and to determine the roles of thrombin and activated coagulation factor X (FXa) in the release of cytokines and fibronectin from NPFs.

METHODS

NPFs were obtained from patients with CRSwNP, and the messenger RNA (mRNA) and protein expression of PARs in these NPFs were examined. We then investigated whether thrombin or FXa stimulates the release of transforming growth factor (TGF) beta 1, fibronectin, eotaxin-1, interleukin (IL) 6, or IL-8 from cultured NPFs. The effects of PAR agonists on the release of cytokines and fibronectin were also examined.

RESULTS

NPFs expressed the mRNA and proteins of all four PARs: PAR-1, PAR-2, PAR-3, and PAR-4. Both thrombin and FXa significantly stimulated the release of TGF beta 1, fibronectin, eotaxin-1, IL-6, and IL-8 from cultured NPFs. PAR-1 and PAR-2 agonists stimulated the secretion of TGF beta 1, fibronectin, eotaxin-1, IL-6, and IL-8. PAR-3 agonist stimulated the release of TGF beta 1, fibronectin, and eotaxin-1. PAR-4 agonist did not induce the release of these molecules.

CONCLUSION

NPFs play important roles in the pathophysiology of CRSwNP such as in nasal polyp formation and inflammatory cell infiltration by releasing cytokines and extracellular matrix proteins. Activated coagulation factors, thrombin and FXa, stimulate the release of these cytokines and fibronectin from NPFs via PARs.

HMGB1-TLR4 signaling contributes to the secretion of interleukin 6 and interleukin 8 by nasal epithelial cells

BACKGROUND

Alarmins play important roles in the pathogenesis of inflammatory and autoimmune diseases. However, the role of the alarmin protein high-mobility group box 1 (HMGB1) in upper airway inflammation is unclear.

OBJECTIVE

To determine if HMGB1 is present in the nasal mucosa and, if so, to elucidate its role in upper airway inflammation.

METHODS

Nasal secretions were collected from a total of 32 patients with chronic rhinosinusitis with nasal polyp, allergic rhinitis, and control subjects. The concentration of HMGB1 in nasal secretions and its tissue and cellular localization were examined by enzyme immunoassays and immunofluorescent staining of nasal polyps and cultured nasal epithelial cells. We then examined whether nasal epithelial cells secrete HMGB1 after inflammatory stimulation by tumor necrosis factor (TNF) α. The effects of HMGB1 on the production and secretion of interleukin (IL) 6 and IL-8 were also examined in cultured nasal epithelial cells.

RESULTS

Significantly higher concentrations of HMGB1 were found in nasal secretions from patients with chronic rhinosinusitis with nasal polyp or allergic rhinitis compared with the control subjects. HMGB1 expression was localized in the nuclei of epithelial cells and other constitutive cells in nasal polyps and in the nuclei of cultured nasal epithelial cells. TNF-α stimulated the production and secretion of HMGB1 by cultured nasal epithelial cells. HMGB1 stimulated the production and secretion of IL-6 and IL-8 by cultured nasal epithelial cells, and anti-toll-like receptor 4 blocking antibody significantly inhibited HMGB1-induced secretion of IL-6 and IL-8.

CONCLUSIONS

Nasal secretions contain substantial amounts of HMGB1. TNF-α stimulates the production of HMGB1, which, in turn, upregulates the production and secretion of IL-6 and IL-8 by nasal epithelial cells via toll-like receptor 4, which indicated that HMGB1 plays an important role in the pathogenesis of upper airway inflammation.

Group 2 innate lymphoid cells are increased in nasal polyps in patients with eosinophilic chronic rhinosinusitis

ILC2s represent a critical innate cellular source of type 2 cytokines and may play important roles in various diseases. We examined the role of ILC2s in the pathogenesis of two subgroups of CRSwNP: ECRS and non-ECRS. We analyzed the prevalence of ILC2s in sinonasal tissues and in blood from patients with ECRS, non-ECRS, CRSsNP, and control. The prevalence of ILC2s in nasal tissues was higher in patients with ECRS as compared to those with non-ECRS or CRSsNP. The prevalence of blood ILC2s was not different between patients with ECRS and non-ECRS. The prevalence of blood ILC2s was higher in patients with allergic rhinitis and elevated serum IgE levels. Alternaria-induced IL-33 secretion was increased in nasal epithelial cells derived from patients with ECRS as compared to those from patients with non-ECRS or CRSsNP. ILC2s may be involved in the pathogenesis of CRSwNP, in particular in patients with tissue eosinophilia (i.e., ECRS).

Tissue factor and tissue factor pathway inhibitor in nasal mucosa and nasal secretions of chronic rhinosinusitis with nasal polyp

BACKGROUND

Activation of the coagulation system with an increase in thrombin generation is involved in the pathogenesis of tissue remodeling in chronic rhinosinusitis (CRS). Tissue factor (TF) is an important protein for initiation of the extrinsic coagulation pathway, and TF pathway inhibitor (TFPI) is a regulator of TF-induced coagulation. This study was conducted to elucidate the roles of TF and TFPI in the pathogenesis of CRS.

METHODS

Tissue localization of TF, TFPI, and fibrin was determined by immunostaining of nasal polyps and inferior turbinates obtained during endonasal surgery in patients with CRS with nasal polyp (CRSwNP). Nasal secretions were collected from patients with CRSwNP, allergic rhinitis, and from control patients. The concentrations of TF and TFPI were measured in nasal secretions from each group. The concentrations of TF and TFPI released into culture medium by normal human nasal epithelial cells treated with thrombin, protease-activated receptor 1 agonist peptide, or tumor necrosis factor α were also measured.

RESULTS

TF expression was localized in nasal epithelial cells and in infiltrating eosinophils of nasal mucosa. TFPI expression was localized in nasal epithelial cells, and fibrin deposition was observed in nasal secretions and the lamina propria of nasal polyps. Nasal secretions contained significant concentrations of TF and TFPI. The concentration of TFPI in nasal secretions correlated positively with thrombin activity and the concentration of thrombin-antithrombin III complex. Treatment with thrombin, protease-activated receptor 1 agonist peptide, or tumor necrosis factor α stimulated significant release of TF and TFPI from cultured nasal epithelial cells.

CONCLUSIONS

By upregulating the coagulation system, TF and TFPI play an important role in the pathogenesis of CRSwNP.

Eosinophil-epithelial cell interactions stimulate the production of MUC5AC mucin and profibrotic cytokines involved in airway tissue remodeling

BACKGROUND

Predominant eosinophil infiltration and tissue remodeling are common characteristics of chronic airway inflammation such as nasal polyposis and bronchial asthma. This study was designed to elucidate the role of eosinophils in tissue remodeling of chronic airway inflammation; eosinophil-epithelial interactions were examined by the coculture of airway epithelial cell line NCI-H292 with the eosinophilic cell line EoL-1 or with human blood eosinophils.

METHODS

The coculture-induced production of MUC5AC mucin, platelet-derived growth factor AB (PDGF-AB), vascular endothelial growth factor (VEGF), transforming growth factor (TGF) beta1, and interleukin-8 (IL-8) were evaluated by enzyme-linked immunosorbent assay and reverse transcription-polymerase chain reaction.

RESULTS

Eosinophil-epithelial interactions significantly stimulated the secretion of MUC5AC, PDGF-AB, VEGF, TGF-beta1, and IL-8 in culture supernatants. The epidermal growth factor receptor tyrosine kinase inhibitor AG1478 inhibited the coculture-induced secretion of MUC5AC, PDGF-AB, VEGF, and IL-8. Neutralizing antibodies directed against TGF-alpha or amphiregulin and pan-metalloproteinase inhibitor GM6001 inhibited the coculture-induced secretion of MUC5AC and amphiregulin from the cocultured NCI-H292 cells. Coculture of NCI-H292 cells with peripheral blood eosinophils also significantly stimulated MUC5AC production.

CONCLUSION

The results of this study indicate that eosinophil-epithelial cell interactions are important in the pathogenesis of tissue remodeling of eosinophil-predominant airway inflammation such as occurs in nasal polyposis and bronchial asthma.

Anti-inflammatory effects of a novel non-antibiotic macrolide, EM900, on mucus secretion of airway epithelium

OBJECTIVE

Low-dose, long-term use of 14-membered macrolides is effective for treatment of patients with chronic airway inflammation such as diffuse panbronchiolitis or chronic rhinosinusitis. However, long-term use of macrolides can promote the growth of drug-resistant bacteria, and the development of anti-inflammatory macrolides that lack antibiotic effects is desirable. Previously, we developed EM900, a novel 12-membered erythromycin A derivative, which has potent anti-inflammatory and immunomodulatory activities and lacks any antibacterial activity. We examined the anti-inflammatory effects of EM900 on mucus secretion from airway epithelial cells.

METHODS

To examine the in vivo effects of EM900 on airway inflammation, we induced hypertrophic and metaplastic changes of goblet cells in rat nasal epithelium via intranasal instillation of lipopolysaccharides. In vitro effects of EM900 on airway epithelial cells were examined using cultured human airway epithelial (NCI-H292) cells. Mucus secretion was evaluated via enzyme-linked immunosorbent assays with an anti-MUC5AC monoclonal antibody.

RESULTS

Oral administration of EM900 or clarithromycin (CAM) significantly inhibited LPS-induced mucus production from rat nasal epithelium. EM900, CAM, or erythromycin significantly inhibited MUC5AC secretion induced by tumor necrosis factor-α from NCI-H292 cells. MUC5AC mRNA expression was also significantly lower in EM900-treated cells.

CONCLUSION

These results indicated that a novel non-antibiotic macrolide, EM900 exerted direct inhibitory effects on mucus secretion from airway epithelial cells, and that it may have the potential to become a new anti-inflammatory drug for the treatment of chronic rhinosinusitis.

Airway uric acid is a sensor of inhaled protease allergens and initiates type 2 immune responses in respiratory mucosa

Although type 2 immune responses to environmental Ags are thought to play pivotal roles in asthma and allergic airway diseases, the immunological mechanisms that initiate the responses are largely unknown. Many allergens have biologic activities, including enzymatic activities and abilities to engage innate pattern-recognition receptors such as TLR4. In this article, we report that IL-33 and thymic stromal lymphopoietin were produced quickly in the lungs of naive mice exposed to cysteine proteases, such as bromelain and papain, as a model for allergens. IL-33 and thymic stromal lymphopoietin sensitized naive animals to an innocuous airway Ag OVA, which resulted in production of type 2 cytokines and IgE Ab, and eosinophilic airway inflammation when mice were challenged with the same Ag. Importantly, upon exposure to proteases, uric acid (UA) was rapidly released into the airway lumen, and removal of this endogenous UA by uricase prevented type 2 immune responses. UA promoted secretion of IL-33 by airway epithelial cells in vitro, and administration of UA into the airways of naive animals induced extracellular release of IL-33, followed by both innate and adaptive type 2 immune responses in vivo. Finally, a potent UA synthesis inhibitor, febuxostat, mitigated asthma phenotypes that were caused by repeated exposure to natural airborne allergens. These findings provide mechanistic insights into the development of type 2 immunity to airborne allergens and recognize airway UA as a key player that regulates the process in respiratory mucosa.

Transcription of interleukin-25 and extracellular release of the protein is regulated by allergen proteases in airway epithelial cells

Epithelial cells at mucosal surfaces are integral components of innate and adaptive immunity. IL-25 is reportedly produced by epithelial cells and likely plays vital roles in regulating type-2 immune responses. However, little is known regarding the mechanisms that control production and extracellular releases of IL-25. We hypothesized that proteases from the multiple allergens may induce IL-25 production in airway epithelial cells. In this study, we found that IL-25 is constitutively produced and detectable in cytoplasm of resting normal human bronchial epithelial (NHBE) cells. When exposed to airborne allergens such as house dust mite (HDM), stored IL-25 was released rapidly to the extracellular space. IL-25 release was not accompanied by cell death, suggesting involvement of active secretory mechanism(s). HDM also enhanced IL-25 mRNA transcription, which was dependent on their protease activities. Furthermore, activation of NHBE cells with authentic proteases, such as trypsin and papain, or with a peptide agonist for protease-activated receptor 2 was sufficient to enhance IL-25 mRNA transcription and protein. Protease-driven increase in mRNA transcription and allergen-driven extracellular release of IL-25 protein was also observed in primary nasal epithelial cells from healthy individuals. These findings suggest that IL-25 production by airway epithelial cells is regulated by the transcription and protein release levels and that allergen proteases likely play pivotal roles in both biological processes.

Role of thrombin in chronic rhinosinusitis-associated tissue remodeling

BACKGROUND

Thrombin, the effector enzyme of the coagulation system, has been reported to promote inflammatory responses in nasal diseases through its protease-activated receptors (PARs). Chronic rhinosinusitis (CRS) is characterized by increased deposition of extracellular matrix proteins, tissue remodeling, and formation of nasal polyps. The role of thrombin in chronic nasal inflammation-associated tissue remodeling still has not been appraised. This study was conducted to elucidate the role of thrombin in the pathogenesis of CRS.

METHODS

Nasal secretion was collected from patients with CRS with nasal polyp (CRSwNP) with asthma (n = 9), CRSwNP without asthma (n = 10), allergic rhinitis (n = 7), and control patients (n = 3). The concentrations of thrombin, thrombin-antithrombin (TAT) complex, and vascular endothelial growth factor (VEGF) were evaluated by enzyme immunoassays. The concentration of thrombin and TAT complex was measured in nasal secretion from each group of patients, and VEGF was measured in culture medium from airway epithelial cells treated with thrombin or thrombin receptor agonist peptide.

RESULTS

Thrombin and TAT complex were significantly increased in nasal secretion of patients with CRSwNPs with asthma compared with the control group. Thrombin and PAR-1 agonist peptide significantly stimulated VEGF secretion from cultured human airway epithelial cells.

CONCLUSION

The results of this study showed that there is increased activation of the coagulation system in the nasal mucosa of CRS patients and that thrombin may play a role in nasal polyp formation by stimulating VEGF production from airway epithelial cells.

Heparin inhibits mucus hypersecretion in airway epithelial cells

BACKGROUND

Heparin is one of the most important anticoagulant drugs. It has been known that heparin also possesses anti-inflammatory activities. Mucus hypersecretion is an important characteristic of airway inflammation. However, little is known about the regulatory effects of heparin on mucus hypersecretion in airway epithelial cells. To elucidate the anti-inflammatory function of heparin in airway epithelial cells, we examined the in vivo effects of heparin on mucus hypersecretion and neutrophil infiltration in rat nasal epithelium. We also examined the in vitro effects of heparin on mucin production and IL-8 secretion from cultured human airway epithelial cells.

METHODS

We induced hypertrophic and metaplastic changes of goblet cells in rat nasal epithelium by intranasal lipopolysaccharide (LPS) instillation. The effects of intranasal instillation with heparin on mucus production and neutrophil infiltration were examined. in vitro effects of heparin on airway epithelial cells were examined using cultured NCI-H292 cells. Mucus secretion was evaluated by enzyme-linked immunosorbent assay using an anti-MUC5AC monoclonal antibody.

RESULTS

Intranasal instillation with unfractionated heparin (UFH; 100 IU/0.1 mL) or low molecular weight heparin (LMWH; 100 IU/0.1 mL) at 30 minutes before LPS instillation significantly inhibited LPS-induced mucus production and neutrophil infiltration in rat nasal epithelium. UFH or LMWH inhibited tumor necrosis factor alpha (10 ng/mL)-induced secretion of MUC5AC and IL-8 from NCI-H292 cells in a dose-dependent manner (0.01-10 IU/mL). MUC5AC mRNA expression was also significantly inhibited.

CONCLUSION

These results indicate that heparin inhibits airway mucus hypersecretion in airway epithelial cells directly and indirectly through the suppression of IL-8 secretion and neutrophil infiltration.

[Endoscopic ligation of maxillary and sphenopalatine artery for intractable epistaxis]

We report the endoscopic ligation of the maxillary and sphenopalatine arteries for the treatment of intractable epistaxis. From March 2003 to February 2005, 17 patients (12 men, 5 women) with epistaxis were hospitalized in our department. Patient age ranged from 25 to 83 years, with an average age of 62 years. 8 patients were successfully treated using the conventional packing method, 2 patients were treated using electrocauterization, and 1 patient with macroglobulinemia was treated using plasma exchange therapy. 6 patients underwent endoscopic ligation of the maxillary and sphenopalatine arteries while under general anesthesia. The post operative courses were uneventful, and no recurrent bleeding has been noted. Endscopic ligation of the maxillary and sphenopalatine arteries is safer than intraarterial embolization and less invasive than conventional surgical approach for the ligation of maxillary artery. This technique appears to be a safe and effective surgical treatment for patients with intractable epistaxis.

[Endoscopic resection of benign and malignant tumors in the nasal cavity and paranasal sinus]

Endoscopic resection of nasal and paranasal sinus tumors is more aesthetic and less invasive than conventional resection, such as Luc's operation and lateral rhinotomy. We clarified the effect of radical endoscopic tumor excision and the control of local bleeding hazardous in endoscopic surgery. Subjects were patients with benign lesions in the nasal cavity, medial wall of the maxillary sinus, ethmoid sinus, and/or sphenoid sinus without concurrent malignant lesions. Although patients selection for malignant tumor excision was based on (1) possible en bloc resection, (2) low-grade malignant tumors, and (3) tumors in the nasal cavity and adjoining paranasal sinus, the final decision was made individual. Subjects were 23 patients with benign tumor (10 inverted papilloma, 9 hemangioma, 2 juvenile angiofibroma, and 2 other tumors) and 4 with malignant tumor (olfactory neuroblastoma, acinic cell carcinoma, squamous cell carcinoma, and chondroid chordoma) in the nasal and paranasal sinus. The tumor was resected en bloc except for patients with inverted papilloma (2 cases) and chondroid chordoma. Recurrence in benign tumors was zero during a mean observation of 21 months. One with chondroid chordoma, however, suffered a recurrent lesion 7 months after the initial operation. The lesion was successfully salvaged by a similar endoscopic procedure and subsequently treated with electron beam irradiation. Preoperative arterial embolization, laser coagulation, and ligation of the sphenopalatine artery were very useful in reducing blood loss during surgery and maintaining a clear endoscopic view. In intraoperative bleeding volume, less than 100 ml of bleeding occurred during surgery in 23 of 27 patients. The endoscopic excision of benign lesions in the nasal and paranasal sinus is thus as effective as conventional radical surgery. Endoscopic removal of malignant lesions remains controversial because of the small number of patients and short postoperative observation.